The world’s food crisis, where 1 billion people are already going hungry and a further 2 billion people will be affected by 2050, is set to worsen as increasing heatwaves reverse the rising crop yields seen over the last 50 years, according to new research.

Severe heatwaves, such as those currently seen in Australia, are expected to become many times more likely in coming decades due to climate change. Extreme heat led to 2012 becoming the hottest year in the US on record and the worst corn crop in two decades.

New research, which used corn growing in France as an example, predicts losses of up to 12% for maize yields in the next 20 years. A second, longer-term study published on Sunday indicates that, without action against climate change, wheat and soybean harvests will fall by up to 30% by 2050 as the world warms.

“Our research rings alarm bells for future food security,” said Ed Hawkins, at the University of Reading, who worked on the corn study. “Over the last 50 years, developments in agriculture, such as fertilisers and irrigation, have increased yields of the world’s staple foods, but we’re starting to see a slowdown in yield increases.”

He said increasing frequency of hot days across the world could explain some of this slowdown. “Current advances in agriculture are too slow to offset the expected damage to crops from heat stress in the future,” said Prof Andy Challinor, at the University of Leeds. “Feeding a growing population as climate changes is a major challenge, especially since the land available for agricultural expansion is limited. Supplies of the major food crops could be at risk unless we plan for future climates.”